1. Field of the Invention
The present invention relates to an LED head suitable for use in LED printers and particularly to such an LED comprising an integrated combination of heat radiating plate and head cover.
2. Description of the Related Art
The LED head is used to focus and image irradiating light from an array of light emitting elements onto a photosensitive drum, the irradiating light being condensed by an array of lenses. One of the conventional LED heads is shown in FIGS. 5A and 5B.
Referring to FIGS. 5A and 5B, the prior art LED head 20 comprises a circuit substrate 21 on which a light emitting element and drive IC are mounted; an array of lenses 22 for condensing the irradiating light from the light emitting element; a head cover 23 supporting the circuit substrate 21 on its underside and also supporting the lens array 22 spaced above the light emitting element and a given distance apart; and a heat radiating plate 24 fixedly secured on the underside of the circuit substrate 21 and adapted to radiate heat from the circuit substrate 21.
The circuit substrate 21, head cover 23 and heat radiating plate 24 are placed one on top of another and are firmly held in place by a mounting spring 25, as shown in FIG. 5B. The LED head includes three of such mounting springs 25 which are spaced away from one another in the longitudinal direction of the LED head.
The head cover 23 includes a reference pin 23.sub.-1 downwardly extending from the bottom face thereof while the circuit substrate 21 includes a through-hole 21.sub.-1 formed therethrough. By inserting the reference pin 23.sub.-1 into the through-hole 21.sub.-1, the lens array 22 can be properly positioned relative to the circuit substrate 21.
As described hereinbefore, the LED head includes a separate heat radiating plate 24 for radiating heat from the circuit substrate 21, in addition to the circuit substrate 21, lens array 22 and head cover 23.
Therefore, the number of parts is increased by the heat radiating plate, resulting in an increase of the manufacturing cost. Furthermore, the heat radiating plate contributes to increase the overall weight of the LED head .